<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        html{
            font-size:50px;
        }
        div{
            font-size:1rem;
            width:10rem;
            height:2rem;
            color:#fff;
            text-align: center;
            line-height:2rem;
            background:red;
        }
    </style>
</head>
<body>
    <div>
        你好
    </div>
</body>
</html>